On Mammoth Mountain, avalanche control requires bringing out a big gun — the 105-millimeter Howitzer

Rescuing skiers and backcountry trekkers is a life’s work for men like ski patrolman Cliff Klock and U.S. Forest Service emergency response expert Jeffrey Karl.

On Mammoth Mountain, a Sierra peak synonymous with snow, they also have a time-tested approach for dealing with avalanche hazards: They shoot at them with a 105-millimeter howitzer leased from the U.S. Army.

If Klock and Karl take you along on gun duty, be prepared to follow a bumpy route through whiteout conditions to a squat concrete and steel bunker perched halfway up the mountain that attracts about 1.3 million skier visits a year.

On Sunday, their mission was to blast slopes over snowy overhangs that had developed overnight and could fall, triggering avalanches.

As a lightning storm pummeled the surrounding countryside before dawn, they took the wraps off the World War II-era weapon, then set to work methodically checking its sights, barrel and mounts. They even kicked its tires.

Hinges groaned as Karl opened a heavy steel door to reveal a basement room known as the “wine rack.”

That’s because unarmed projectiles are stored horizontally in its walls like wine bottles.

Together, they assembled the shells and screwed in the detonators. Drawing on decades of records and years of experience with the forces that transform pile powder into dangerous unstable mounds, Klock planned to launch 15 rounds into the mountain about 300 miles north of Los Angeles, just off Highway 395.

 Around 5:30 a.m., Klock said, “All right, let’s start shooting.”

Wind and snow blew into the cramped room when the men opened a garage-style door. Then they wheeled the howitzer around on its wheels, pointing the barrel toward the howling darkness beyond.

“This gun is so precise it’s like shooting at point blank range,” Klock said. “I could hit a rock at 1,000 yards.”

But at that moment he was relying on carefully calibrated coordinates to fire on the first target on his list: a popular ski run that is also a potential avalanche path.

Klock yelled, “Fire!” and the fearsome gun roared, lifting off the ground. A few seconds later, the whump of the impacting shell drifted back.

Ear muffs over ear plugs minimized the blast effects of all 15 rounds fired at target areas that were off-limits to the public.

The howitzer is only used when conditions warrant, which differ year to year, Mammoth Mountain officials said. It was rarely needed, for example, during the drought-parched years of 2011 through 2014.

A howitzer once again became a vital component of the Mammoth Mountain operation in the snowy winter of 2015, officials said.

Decades ago, the military provided Mammoth and other ski areas with old-style recoilless rifles for controlling avalanches. But ammunition became hard to get, and in 2003 the Army decided to swap them for two-wheeled, truck-towed M-119 A-1 howitzers, officials said.

A year later, however, the U.S. military reclaimed the howitzers it had leased for avalanche control, including the one at Mammoth Mountain, so that the weapons could be used by troops fighting in Iraq and Afghanistan.

The howitzer recalled from Mammoth Mountain in 2004 never came back. Instead, the Army replaced it later with the vintage weapon that saw action Sunday.

The Forest Service and Mammoth Mountain, which has received 10 feet of fresh snow over the last week, has one of the world’s most respected programs for avalanche prevention and warning.

But the staff had their hands full Sunday because of unpredictable weather associated with this weekend’s atmospheric river event — a brew of warm torrential rains and heavy snow — and the surging popularity of winter recreation at the ski area.

Mammoth Mountain officials decided at 11 a.m. Sunday to shut down the ski area because lightning strikes made it impossible to continue operating.

As a result, Klock and Karl would never get to ski the fruits of their bombardment.

“As great as that gun is,” Klock said. “It can’t do anything about lightning.”

louis.sahagun@latimes.com

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